System of control



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INYENTOR L/oyad/flbbard n'usssss; %(/M ATTORNEY Patented Oct. 27, 1925.

UNITED STATES PATENT Zorn-ca.

anaemic'e'rrii'nuracroame'oor rAivY/A CQBPQBAT'IQN orllnnnsynvanm.

SYSTEM O 99 11.??-

Original application filed December 17, 1919, Serial No. 345 486. Divided and. this application filed October 24, 1923.

To ail whom it may concern.

Be it known that I, LLOYD J. HIBBARD, a citizen of the United States, and a resident of Vilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Systems of Control, of which the following is a specification, this application being a division of my application Serial No. 3%,),486, filed December 17, 1919.

My invention relates to systems of control for dynamo-electric machines, and it has special relation to the control and inter locking of the operation of a plurality of alternating current commutator motors during the accelerating period.

' An object of my invention 18 to prov de an auxiliary governingsystem for effecting reliable and proper sequential operation of a plurality of switching devices for gov: erning the motoring operation of a set or single-phase commutator motors.

Another object of my invention to providea system of the above-mentioned character, having meansfor maintaining desirable vcomi'i'iutating conditions through a Wide range ofoperation.

Other specifi'c'objects of my invention, relating to the improved interlocking or auxiliary control functions, Will become evident from the following detailed description talgen in conjunction vvith the accompanying draivings, wherein Figure 1 is a diagrammatic View of a substantially complete main-circuit control system organized in accordance with the principle s'fset forth in the above-identified cripfiding application;

Fig. 2 is a diagrammatic view of my auxiliary governing circuits for the main 'control system of Fig. 1;

Fig. 3 is iii-"sequence chart, of welllznown form, indicating the prefeired order of operat ion of thesevcral switches;

Fig. 4 is a diagrammatic detail view of one of the'un-itsivitches that is employed in n y invention; Fig. 515' a semidiagrammatic view showing the preferred construction of one ofthe ea ement-11erstestis utilized in the preseatiinvnaon; and" phase converter field-Winding current.

Serial No. 670,452.

Fig. 6 is a diagrammatic view of. an interlocking system that is preferably employed in connection with the operation of one portion of my invention.

The'general operation of the dynamo-electric machines that are controlled in accordance with my present invention may be set forth as follows. The motors are connected in parallel relation during the accelerating period and the applied'voltage from the supply transformer is gradually increased by manipulation of the main master controller. In case of low voltage, the overspeed drum may then be operated to en large the transformer section that is connected across the motors.

'The main field windings are separately excited during'the regenerative period by means of the resultant voltage that is obtained from'the secondary winding of the and a section of the supply transformer. Regeneration is accomplished by varying the phase relation between the armature land the field Winding currents in such manner that acoinponent of the armature current is 180 out of phase Withthe The phase relation of the armature current is automatically controlledthrough' the agency of a powerfactor relay device, which maintains the current phase at a predetermined angle to the line voltage. The phase relationof the field current is manually controlled from .the main master'contl'oller to thereby govern the regenerative tractive effort of the locomotive.

Referring to Fig. 1 of the drawings, the system hereshown comprises a plurality of single-phase motors of the commutator type 1M7 and M10, which are respectively .pro-

.videcl'with armatures A7 and A10, main or exciting field windings F7" and F10, compensating or inducing field-windings G7 and ClOand in'terpole or'cpmmutat-iiig field ,irindings I7 and 110, the motors being Jselectivelyconnected through switches 3to 6, inclusive, 11 told, inclusive, 17 22 inclusive, 2-", 26, E20. 30, 33, 34, 87, and 38 and other apparatus through switches 41, 43, "4 4i and 116 the secondary .ivin'ding'51of a supply transformer of a famih'artype.

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The system further comprises a plurality of transformer taps 52, 54 to 56, inclusive, and 58 that are associated with the field power-factor regulating switches 13, 1d, 17 to 22, inclusive, 25 and 26 the correspond ing portions of the supply transformer being connected, during the regenerative period of the main motors, in series relation with the secondary or generating phase of the phase-converter that is interposed between the commutating machines and the supply transformer winding to effect re generative operation of the machines.

Further taps 7 6, 77, and 81 upon another section of the transformer winding 51, are associated with the speed-regalating switches 3 to 6, inclusive, 11 and 12 and serve to connect selected portions of the transformer to the armatures of the commutator machines. The switches 3 to 6', inclusive, and 11 and 12 are employed during the motoring period for varying the voltage impressed across the'main motors, whereby the speed thereof be controlled. The switches are also used to vary the voltage ap plied to the interpole field windings I7 and I10. During the regenerating period, switches 3 to 6 inclusive, 11 and 12 are .automatically controlled through the agency of a power-factor relay (designated as 70 in Fig. 2) and a sequence drum (designated as 73 in Fig. 2), whereby the voltage across the motor armature and a main field auxiliary exciting transformer 91 is suitably varied to maintain the'armature current in a predetermined phase relation with the line voltage, as fully explained in the Patent 1,440, 190 granted to L. M. Perkins January the 2nd,'1923. p

A phase converter 82 is provided with a stator 83 having quadrature-related motoring and generating windings and av co-operat-ing rotor er having a winding that is adapted for direct-currentexcitation: or, in other words, the phase-converter is prefer ably of the synchronous type. It is not be lieved tobe necessary to describe or explain the operation of the phase-converter 82 beyond stating that one stator winding thereof isconne'cted across a predetermined section of the transformer winding to operate the converter as a synchronous'motor; where- 'as a quadrature-related"stator winding generates a voltage by reason of cutting the flux set up by the direct-currentrotor windin and such generated voltage is employed f o assist in exciting the main field windings of the motors during the regenerative period.

For the purpose of preventing undue surges of current while shifting from one transformer tap to another, preventive coils 85 and 86 are associated with the switches 13, 17 :to 22, inclusive, 25 and 26 in a familiar ,mannerfwhile corresponding pre-. ventive coils 88 and 89 are connected in cir;

.19 to 22 are controlled cuit with the switches 3 to 6, inclusive, .11 and 12.

The above-mentioned main field auxiliary exciting transformer 91 is provided with a secondary coil 92 which is connected in series relation with the primary winding of the stator 83 of the phase-converter 82. A cooperating or primary winding 93 of the auxiliary transformer 91 is connected between the preventive coils 88 and 89 and transformer tap 80, a normally open switch 50 being interposed in the circuit.

An inter-pole field transformer 94: is provided with a primary winding 95 that is connected between the preventive coils 86 and 89 and one end-tap 81 of the supply transformer 51, a plurality of switches 13 and a4- serving to connect dif erent portions of the .interpole transformer winding 95 in circuit, for a purpose to be hereinafter set forth. The secondary winding 96 of-the inter-pole field transformer is connected in shunt relation to the interpole field windings of the motors, which windings are here shown for the sake of simplicity and convenience as embodying a single coil, such as that marked 17 and 110.

A series or current transformer 97 is connected in the main motor circuit, that is, in series relation with-the secondary winding 92 of the main field exciting transformer 91, for the purpose of overning a plurality of relay devices er and 66, as subsequently set forth in detail. Furthermore, a oalancing relay 69 is continually shunted across the terminals of the switch 34c and is instrumental in connecting the machines to the supply circuit when the relative voltage conditions thereof are proper.

During the motoring period, the switches by the Overspeed lever of the master controller and are used. to provide additional speed notches under low trolley-voltage conditions, when fullspeed operation cannot be obtained by means of the principal speed lever or handle.

' During the regenerative period, the regulating switches 13, 14, 1T22, inclusive, 25 and 26 are controlled directly by the main speed lever of the master controller and are used to vary the phase relation between the resultant voltage that is applied to the main field windings and the line voltage, which variation, in turn, effects regulation of the regenerated torque of the locomotive.

The switches 29 and 80 are controlled directly by the main speed lever of the master controller and are used to disconnect the main field windings from the armature during the regenerative period, while, during? the motoring period, they are closed.

Switches 3 3 and 54 are employed to connect the motor armatures to the supply circuit during the regenerative period. They are controlled by the main speed: lever of the master controller and also by means of a set of contact members upon the voltage balancing relay 69. This relay prevents the switches from closing when more than a predetermined value of voltage obtains across the line switch 34 and hence prevents a current or torque surge when the machines are connected to the line.

Switches 37 and 38 are used to connect the main field windings across the generator winding of the phase converter and a section of the supply transformer during the regenerative period. These switches'are controlled by the main speed lever of the master controller.

3 Switches 43 and 44 are used to vary the voltage applied to the interpole field windings IT to I10 of the motors. These switches are automatically controlled by current relays 64 and 66.

A plurality of switches R9 to R16, inclu, sive. are employed for reversing the main field windings of the motors and are controlled by the reversing lever of the master controller. These switches are closed in alternate pairs to provide the desired connection, as subsequently more fully described.

The main field auxiliary exciting transformer 91, as fully explained in Patent 1,440,490 to L. M. Perkins, is employed to automatically vary the phase relation of the voltage applied to the main field windings in such manner as to change the slope of the speed curves of the motor and afford a greater operating range in accordance with each curve. Consequently, the total number of switches that are required for covering a given range in locomotive speed is mate'- rially decreased.

The interpole field transformer 94 is employed in conjunction with the speed-regulating switches 3 to 6, inclusive, 11 and 12, 43 and 44, to vary the voltages impressed upon the inter-pole field windings I7 and 110. inversely with the speed of the motor and directly with the armature current, whereby desirable commutation in the motors is maintained over a wide range. The switches 3 to 6, inclusive, 11 and 12 operate to decrease the voltage across the primary winding 95 of the interpole field trans former as the switcnes are manipulated to increase the motor speed, while switches 43 and 44 automatically vary the voltage impressed upon the transformer in accordance with the variations of armature current.

Referring to Fig. 2 of the drawings, the

. auxiliary governing system shown comprises the actuating coils of the various switches that are shownin Fig. 1, together with a plurality of electrical interlocks of the familiar type that is illustrated in Fig. 4 in connection with the switch 33 and primary controlling apparatus mcluding a control battery B, a master controller main drum MC, a master reverser MR, and an overspeed controller 61. Further control of the auxiliary circuits is effected by means of a plurality of relay devices, already mentioned in connection with Fig. 1, and also through the agency of the sequence drum 7 3, which is driven by a pilot motor that is controlled by the power-factor relay 70.

The master controller MC is provided with seven operative positions a to g, inclusive, corresponding to motoring or acceleration, these positions being located on one side of an oil? or neutral position, while, for regeneration, nine operative positions 0, to 1'. are arranged on the opposite side of the 01f position. A suitably configured contact segment 101 is placed on the motoring side of the controller for the purpose of engaging a plurality of control fingers 102, 105 to 108, inclusive, 113 to 116, inclusive. in a n'edetermined sequence. In a similar manner, a contact segment 117 is provided upon the regenerative side of the master controller to engage a plurality of control fingers 118 to 1520, inclusive, 123 to 128, inclusive, and 131 to 133, inclusive.

In addition, a plurality of overspeed contact segments 134 to 137 are provided upon the master controller and are respectively associated with pairs of control fingers 138, 139, 140 and 141. The preferred construction of the master controller to provide the desired connections is indicated in Fig. 5, whereby it will be seen that the motoring contact segment 101 and the overspeed contact segment 134 are located opposite each other on the control drum, while the regenerative control fingers 118 and the overspeed control fingers 138 are disposed in substantially the same plane. The purpose of this construction will become evident from the following detailed description.

The overspeed drum 61 normally occupies position a, as illustrated, and is adapted to be actuated through positions 1 and a, for purposes hereinafter described in detail.

The sequence drum 73 normally occupies a position 2' and is adapted to occupy other operative positions h" to a, inclusive. A contact segment 142 selectively engages a plurality of control fingers 143 to 147. in elusive, while other control lingers 150 to 153. inclusive, and 157 to 159. inclusive. eugage a contact sefzn'ient 14 in a predetcrmined order.

The sequence drum 73 is driven by a pilot motor 160 having an exciting field winding 163 and a commutator type armature 161 that is mechanically connected to the operating shaft 162 of the drum and that may be energized in conjunction with a braking resistor 164 through the agencv of a plurality of reversing relay devices 71 and 72 for governing the starting, stopping and direc IUU tion of movement of the pilot motor. The power-factor relay device 7 O, in turn, governs the operation of the relays 71 and 72 and: is provided with three positions marked Lag, 100%, and Lead, corresponding to the value ofthe power factor that obtains during the operation of the main motors.

As illustrated in Patent 1,440,490 to L. M. Perkins, the power-factor relay T0 is actuated by means of a motor having a twophase stator winding that is connected to the two-phase stator winding of the phase Converter, while the rotor winding of the auxiliary motor is energized in accordance with the current traversing the main motor armature. Since the connections of the auxiliary driving motor form no part of my present invention, 1 have not deemed it necessary to illustrate or specifically explain such connections,-it being understood that the power-factor relay device is automatically actuated in accordance with the power-factor of the main motor system to maintain a predetermined value of powerfactor, preferably through the agency of the reversing relay devices 71' and 72 and the sequence drum 73.

. More specifically described, notches Z) to 72 inclusive, control switches 3 to 6., inclusive, 11 and 12 during the regenerative period. The normal notch e' is provided to ensure that the switches 37 and 38, and 11 and 12 are closed to energize'the voltagebalancing relay 69 before the line switches 33 and 34 have an opportunity to close. Consequently, the last-named switches cannot be closed before the voltage of the main armature has been adjusted to a proper value.

Notch al" is provided to effect an opening of the main-circuit switches in case the motorman throws the main speed lever to bal ancing position a of-the master controller and attempts to. effect regeneration when the locomotive is running at a speed that is too low.

The sequence drum 73 is automatically returned to the illustrated position i, whenever switches 37 and 38 are opened, by reason of the energization of the pilot motor 160 that thereupon occurs. This feature is provided to ensure the proper functioning of the voltage-balancing relay 69 at all times.

The sequence drum 73 is automaticallymoved notch by notch from position Z toward position co" ,when the motorman throws the'main speed lever to balancing posit-ion 0; of the master controller. Such movement continues until the proper voltage, as indicated by the voltage-balancing relay 69, has been attained. In this event, the regenerative line switches 33 and 34', inclusive, are closed to connect the motors to the supply circuit. When these switches have been closed, the sequence drum is directly controlled by the power-factor relay "('0 and is moved back and forth notch by notch as the locomotivespeed varies or as the main speed lever of the master controller is actuated.

The pilot motor 160 is controlled by means of the reversing relay devices 71 and 72 as follows. lVhenever both of the relay devices are energized or both are de-energized, the motor armature is short-circuited through the resistor 164 and is dynamically braked if it is running at the time.v YVhen the relay device "(1 is de-energized and the relay device 72 is concurrently energized, the motor armature is actuated to rotate the sequence drum from position a toward position 6, whereas, with the reverse conditions of the relay devices, the sequence drum is moved in the opposite direction.

The operating coil of relay device 40 is connected in parallel relation'to the operating coils of switches 37 and 38. The relay device is employed for completing the control circuits to the power-factor sequence drum 73, when the regenerative line switches 33 and 34 are open, as hereinafter more fully set forth, and the operation of the relay device is not effected by cutting out a set of motors.

The inter-pole limit switches or current relays 64 and 66 are energized from the series transformer 97 and are adapted to govern the energization of transfer relay devices 65 and 67, respectively, whereby the actuating coils of the switches 43 and 44 are energized and tie-energized to correspondingly vary the energization of the interpole field windings I7 and 110, from the interpole field transformer 94.

The operating coil of the limit relay 64 is set to etl'ect the lifting of the relay device at a current value equal to approximately tVOrtlllIdS' of the combined hour rating of the motors, while the operating coil of the other limit relay 66 is set to operate the relay device at a current value substantially equalto the full combined hour rating of the motors. Consequently, when the mainarmature current equals the critical operating value of the limitswitch 64, the switch 44 is closed to energize the primary winding of the interpole field transformer 94 and thus impress an additional voltage upon the interpole field windings I? and 110, the entire primary winding 95 being connected in circuit. On the other hand, when the limit switch 66'is operated by reason of the traversal of ahigher current through the main armatures, the switch 43 is closed, while switch 44 is opened,-to exclude a portion of the transformer winding 95 from circuit and thus effect increased energi- Zation of the secondary winding 96 of the interpole field transformer and, therefore, an increased current in the interpole field windings I7 and I10 to compensate for the increased current flow in the main armatures.

The operating coil of the voltage balano ing relay 69 is connected across the terminals of switch 3%, as illustrated in Fig 1. Thecontact disk of the relay device is placed in the circuit of the actuating coils of switches 33, 3 and 50, as shown in Fig. 2, to prevent these switches from closing when the voltage across the switch 34 exceeds a predetermined value. In this Way, connection of the momentum-driven motorsftothe supply circuit is prevented unless conditions are suitable to precludea heavysurgeofcurrent by connecting-theInachinesto thefline. Atcr the switch 34: has once been closed, thevoltage relay 69 is tie-energized thereby, and the contact disk of the relay device 1n its lower position acts as a holding circuit for theswitchcs in question,

In the interests of simplicity and-economy,

the lar 'e number of conductors extendine from the several controller drums to the auxiliary circuits have been. grouped in a conduit or wirebundle, cncecharacter 171.

Assuming" that it is desired to effect forward acceleration of'the motors. andthat the master reverser already occupies itsreverse position, Rev., the master reverser is first thrown to its position For., whereupon a circuit is established from the positive .terminalof the battery B through conductor 210,- contact segment 211 of the master .re vcrser, conductors 212 and, 213, where the circuit divides, one branch including-interlocks Bil-out, R12-out, the actuating coils of the switches R9 and'R-lO in parallel and conductors2l4, 215 and 216 to the negative terminalj of the battery B; The reversing switches R9, and R10 are thus closed, pro-. vided the oppositely connected switches R11 audlilQ have been given sufiicient time toopen.

In a similar manner, the corresponding reversing switches R13 and. R14 are closed to connect therest of themain motors for forward operation.

If the master; controller; MC isthen actuated toits initial motoring position: a, a. new circuit is established from the contact seg. ment, 211 of the master reverser units forward position, through conductor 218, junction-point 2l9, conductor 220, contact segs merit-221 in normal position not the overspeed drum-61, conductors. 222 and 223, interlock or contact segment 73 .z'", wher b indicated by referthe circuit under consideration is closed, only when the sequence drum 73 occupiesitsnorinal position i, whence circuit is continued through conductors 225. and 226, con trol gfingers 116-a1id115, which arebridged by contact segment 101 of the master controller, conductors 227 and 227a, contact coil of switch 3 to the segment 228 of the overspeed drum 61, conductor 229, control fingers 138, which are bridged by contact segment 134, from which fingers two parallel circuits extend, one ofwhich includes conductors 230 and 232 interlocks I S-out, la-out and 2250111; and the actuating coil of switch'26tonegative conductor 214, while the other parallel circuit includes conductors and 233, interlocks IB-out, 21-out, l7-0ut and the actuating'coil of the switch 25 to the negative conductor 214;

A further circuit is established from the contact segment 101, in osition a of the main master controller M through. control finger 102, conductors 239 and 2&0, whence two branch circuits are completed respectively including interlocks 33-out, 37-out, actuating coil of switch 29; and interlocks B t-out and 38-0ut and actuating coil of switch 30.

Other circuits established at this time extend from the contact segment 101 of the master controller through circuits respectively including control finger 105, whence circuit is completed through, conductors 256 and 257, interlock ll-out andthe actuating negative conductor 214. i

As indicated in step a of the sequence chart, Fig. 3, switches, 3, 25, 26, 29 and'BO, R9, R10, R13 and R14; are closed under initial motoring conditions of the machines. Referring to Fig. 1, a main circuit is established in this way from intermediate tap of the supply transformer 51, switch a section of the preventive coil 88, conductors 247 and 248, where the circuit divides, one branch including the interpole or commutating field I7, armature A7, inducing :field windingCT, switches 29. and R9, exciting field winding F7, switch R10, conductor 256,.and tl1ence from a terminal of preventive coil 86 through switches 26 to transformer tap 58.

The remaining car-propelling motor M10 is connected in parallel relation to motor M0 as willbe understood without further trac ing thecircuit. In this way,t he commuta tor motors have a predetermined starting voltage impressed across their terminals and the locomotive is gradually started into operation.

In a similar manner, control-fingers 100 30,108, inclusive, 1l3fand 11 i are successively engagedby the contact segment 101 as the master-controller is actuated thr ugh notch- .es 7) to f, inclus'iye, whereby the actuating coils of switches. 4 to 6,;inclu'sive, 11 and 12 are respectively energized to gradually increase the voltage across the motor circuits and thus accelerate the motors to full running speed;

During suchactuation ofithe master controller, certain switches drop out in succession, as indicated in the sequence'chart, to

venting short-circuiting of transformer coils;

In case the trolley voltage is low, the overspeed drum 61 may be actuated, after the mastercontroller MC occupies its position 7', into the second operative position 3 Although contact segment 221 of the overspeed drum is thus cut out of circuit, the intercon-,

nected circuits are not interrupted by reason of the fact that interlock 12-in, actuated by switch 12 in final position f of controller MC, shunts the segment 221. A newcircuit is thereupon establishedfromthe contact segment 228 of the overspeed drum through conductor 268, contact segment 136,which bridges control fingers 140 of the master controller MC, whence circuits are completed through conductors 259 and 260 and the illustrated interlocks to the actuating coils of switches 22 and 21, respectively. 'At the same time,

conductor 229 becomes de-energized by rea-' son of the disengagement of the corresponding control finger from contact segment 228 of the overspeed drum in position y, whereupon switches 25 and 26 are opened.

In this way, a higher voltage tap, namely,

tap 56, is connected in the motor circuit, while the tap 58 is disconnected therefrom to impress a greater Voltage upon the motor terminals and increase the operating speed of the machines.

In case a still higher voltage is necessary to bring the motors to full running speed,

the overspeed drum 61 may be actuated to its position 2 to establish a new circuit from contact segment 228 through conductor 261, contact segment 137, which bridges control fingers l ll of the master controller MC, whence circuit is completed through conductors 262 and 263 to the actuating coils of the switches and 19, inclusive.

Consequently, a still larger section of the supply transformer is connected across the terminals of the motor circuits and the motors may. thus be accelerated to a higher speed 1 l 7 Assuming that it is desired to effect regen erative operation of the system with the master reverser MR occupying its Forward position and the overspeed drum 61 occupying its normal position a", themaster controller MC may be moved to the initial or balancing notch a on the regenerative side of the controller. Previous to such manipulation, it will be understood that the phaseconverter 82 has been started into operation in any suitable manner and that the secondary switch 41 has been closed to render the voltage of the secondary or generator winding of the phase-converter stator 83 ductors 272 and 276, interlocks 17 -out, 2l-out I and -out, the actuating coil of switch 13 and conductors 273 and 277, proper inter locks and the actuating coil of switch 14:.

A further circuit is established from the master controller MC in its balancing position a through control finger 118, conductors 280 and 281, contact segment 7 3- (bi) of the sequence drum, conductor 282, contact segment 7 3# (thus insuring that the sequence drum occupies its normal position before regenerative operation can be effected), whence circuit is continued through conductor 283, parallel-related actuating coils of the switches 37, 38 and 40, conductor 284, interlocks 29-out and -out and thence througlrnegative conductor 214: to the corresponding battery terminal. Up-

on the closure of these switches, holding circuits therefor are formed between conductorsv 282 and 283, comprising parallelvrelated interlocks 37-in and 38-in.

A branch circuit is established from the above-mentioned interlock 7 3-c' through conductors 285 and 286 to control finger 159 and contact segment 142a of the sequence drum 73. Control fingers 158 and 157 and corresponding conductors 287 and 288 are thereupon energized from the contact segment 1 12a, and circuits are continuedtherefrom through conductors 291 and 292, and proper interlocks to the actuating coils of switches 12 and 11, respectively.

Referring temporarily to Fig. 1, the maincircuit connections at this time comprise outer transformer taps 52, switches 13 and Y 14, conductors 295 and 29566, preventive coils 85 and 86, conductor 250, switch R10, exciting field winding F7, switch R9, switch 37, conductor 298, primary winding of the current transformer 97, secondary winding 92 of the main field exciting transformer 91, conductor 299, generating winding of the stator 83 of the phase-converter 82 and conductor 300 to intermediate transformer tap 5%. A similar circuit including the switch 38 and the remaining exciting field winding F10 is concurrently energized by reason of the illustrated parallel relation of the field-winding circuits. In this way, the exciting field windings are energized by the relay 69, which is connected across the terminals of the open regenerative line switch 3%, whence circuit is continued through conductors 301, and 302 to intermediate transformer tap 56. In this way, the voltage of a predetermined section of the supply transformer 51 is opposed to the regenerative voltage of the momentum-driven armature A10, the differential value of these voltages being impressed upon the actuating coil of the voltage-balancing relay 69, which remains in its upper or open-circuit position until these voltages are substantially equal.

The initial or preparatory regenerative voltage is automatically varied, until it substantially equals the voltage. of the corresponding section of the supply transformer, by means of the powenfactor sequence drum 73. This function is accomplished by reason of the establishment of a circuit from the positive terminal of the battery B through conductor 303, control fingers 147 and 146, which are bridged by contact segment 142 of the sequence drum, conductors 304i'and 305, actuating coil of the reversing relay 7'1, conductor 306, interlocks 40,-in and 50 out, conductor '30'7, series-connected interlocks 11-in and 12-in and conductor 308 to the negative battery terminal.

Upon the relay 71 being actuated to its upper position, by reason of the energizing circuit just traced, a circuit is established from the positively-energized conductor 303 through conductor 309, armature 310 of the reversing relay 71, conductor 311, armature 161 of the. pilot motor 160, resistor 164, armature 312 of the reversing relay '72 in its normal or de-energized position, and conductors 313 and 31% to the negative battery terminal.

A further circuit is completed from the conductor 309 through conductor 315 and field winding 163 of the pilot motor to negative conductor 313.

In this way, both the armature and the field windings of the pilot motor 160 are energized in such manner that the powerfactor relay drum 7 3 is gradually actuated toward its position a. By so doing, the control fingers 153 to 150, inclusive, may

be successivelyengaged by the contact segment 142a to energize the conductors leading to the actuating coils of switches 6 to 3, respectively, whereby the section of the ment 32 supply transformer that is connected to the ionientuni-driven armatures is gradually "decreased until a substantial equality obtains between the voltage of that section and the voltage of the arn'iatures. Under such conditions, the actuating coil of the voltagebalancing relay 69 is substanuslly deenergized, causing the relay to drop to its lower or circuit-closing position, whereupon a circuit is continued from the conductor 28% through conductor 320, contact disk 321 of the voltage-balancing relay 69 in its lower position, conductors and 323, the paral- O04 lel-related actuating coils of switches 33 and 3 1', conductor 32%, contact segment 73 (F -i) of the power-factor sequence drum, conductor 325, contact segment T3 (b i), conductor 283, .parallel-related. interlocks 37-in and 38-in, conductor 282 and contact segment 73(bi')- to positively energized conductor-281.

Tn this way, the regenerative line switches 33 and 34 are closed when proper relative voltage conditions of the momentum-driven armatures and the supply circuit obtain, while the closure of line switch 34: shortcircuits the actuating coil of the voltagebalancing relay 69, which subsequently remains in its lower or circuit-closing position to act as a holding circuit for the coils of the line switches.

The switch 50 is also closed at this time to connect the primary winding93 of the main field exciting transformer 91 across a certain section of the transformer that extends between tap and the adjacent active taps-that are connected through the switches 3 'to6, inclusive.

It will be seen that actuationof the master controller to its initial or balancing notch n first closes the switches for energizing the exciting field windings from the generating windingof the phase-converter and a section of the supply transformer, whereupon matically effected. Such switch movements are indicated in step a of the sequence chart,

Fig. 3.

A'ssoon as the voltage-balancing relay 69 hasdropped to its lower position to effect the'abovedescribed closure'of switch 50, the previously-traced circuit through the actuating coil of the reversing relay 71- and interlock 50-out is interrupted. However, con trol of the sequence drum 7 3 is immediately assumed by thepower-factor relay 70, since the actuating coil of the switch 71 is connected through conductor 326, contact seg- 7 of the power-factor relay in its Lag position, conductor 328 and interlock 50-in to negative conductor 307.

' tends to fall below the critical value, preferably 100%, for which the power-factor relay has been previously adjusted- On the other hand in ositions 6 to a of thesequence drum, a new circuit may be established from the contact segment 142 through control finger 145, conductor 329, actuating coil of the reversing relay '72, conductor 330, contact segment 3 31 of the power-factor relay in its Lead position, and conductor 332 to negative conductor 328. Consequently, the reversing relay 72 is actuated to its upper position, while the relay 71 occupies its normal or lower position when ever the power-factor of the regenerating motors tend to increase beyond the abovementioned critical value, whereby the connections of the pilot-motor armature 161 are reversed to cause a reverse movement of the drum 7 3 toward its position i. In this way the desired power-factor relations are automatically re-established.

As indicated in the sequence chart, positions 6 to i, inclusive, the field powerfactor regulating switches 14, 17 to 22, in-

clusive, 25 and 26 are successively closed for certain periods as the master controller.

MG is actuated through its positions I) to i.

In this way, the gradual decrease in speed of the regenerating locomotive during the retardation period may be manually compensated for to maintain a desired value of breaking effort. During such manipulation, the power-factor relay 70 automatically maintains the desired power-factor relations by governing the opening and closure oft-he speed-regulating switches 3 to 6, in clusive, 11 and 12. V

lVhen it is desired to discontinue regenerative operation, the master controller MC may be returned to its off position to open all the switches governed thereby. Under such conditions, the sequence drum 73 is automatically returned to its initial position 2' to insure readiness for the next regenerative operation, through the agency of a circuit that is completed from the actuating coil of the reversing relay 72 through conductor 330, interlock 40-out and conductor 333 to negative conductor 314. Thepilot motor 160 is thus automatically energized to effect the return movement of the drum 73 between positions a and h or any portion thereof, since control fingers 147 and 145 are continuously engaged in such positions by the contact segment 142. As soon as position h is passed, the control of the reversing relay 72 is transferredto another portion of the contact segment 142 and control finger 143, whence the circuit in question is completed through interlock 40-out to conductor 329. In this way,

will the portion of thecontact segment 142 that was employed in connection with control finger 145 during normal forward movement of the sequence drum 73 is employed to return the drum as far as position it and the remaining portion of the backward travel of the drum is effected through the agency of control finger 143 and the cor responding portion of the contact segment 1%.. I V

Thus, whenever the switch or relay 40 opens, the power-factor sequence drum 73 is automatically returned to its position i". If the operating handle or lever of the inastcr controller MC is placed or held on the regenerative notches, the power-factor drum again be automatically rotated step by step from position i" to position a, provided that the locomotive is running at a speed that is too low to effect regeneration. The switches initially closed, including switch 40, will be opened when the drum reaches position a, as previously described. he'opening of switch 40 causes the drum to return to position i", as already set forth. This cycle will be repeated as long as the operating handle in question is held on the regenerative notches and thus will act as a signal to the motorman when the locomotive speed is too low for regenerative operation. This action will also serve to warn the motorman if the operating handle is left on a regenerative notch when the locomotive is at a standstill.

An interlock 50-otut is connected with control finger 144 which engages contact segment 142 of the sequence drum 73 in position b. The function of this interlock is as follows. In case the motorman attempts to effect regeneration at an unsuitably low speed which has caused the sequence drum 73 to be rotated-to its limiting regulating position 7) during the preliminary voltage-balancing period before the switch 50 has been closed by the relay 69, when a circuit is established through the interlock fiO-out in question and the actuating coil of the reversing relay 71 to energize the pilot motor 160 in such a direc tion that the sequence drum is rotated to its extreme position a". Consequently, all of the switches governed by the contact segment 142 of the power-factor drum, namely,

.switches 3 to 6, inclusive 37, 38 and 40, are

coil of transfer relay 65 and conductor 344, while a lunch circuit is continued time conductor 340, through conductor 346, con tact dish 3%? of the av 66, conductor 34 -8 5 and actuating coil of the transfer relay 67, whence a com on circuit for th'ejactuating coils of the 'r l y coils '65 and '6? is Conipleted through conduct r 34.0 to the negative battery termina. Under such ccntli tions, neither of the actuating coils of the switches i3 and t l-i. is energized.

However, in case the critical value for which the relay 6i is set, namely, approxitwo-thirds of the combined hour l5 ratng of the motors is reached, then the relay 61 is actuated to its upper or circuit- 'on to permit the transfer reto its lower or tie-energized Co? aequently, a new circuit is )lishcd from the positively-jeue' .uctor 340, through contact disk 3. t. transfer relay 65, conductor 3:31, con iv. r dish of the other transfer relay in its upper or ener ized position, conductor actuating coil of the snitch and interlock 43-out to the negative battery conductor. Consequently, the entire primary w iding of the intcrpole field transenergized to e'ffect the supera predetermined voltage upon impressed upon the interpolc l? and 110. In case the higher current value for which the. relay 66 is set is attained, the relay is likewise actuated to its upper or circuitopening position, and the consequent dropping of the transfer relay 67 first tie-energizes the circuit of the actuating coil of the switch 4i and closes a new circuit as soon as that switch has opened through contact disks 352 of t re transfer relay 67, conductor actuating coil of the switch 43 and interlock M-out to the negative battery conductor. Consequently, the switch at is opened and the switch 43 is closed to im press a still higher shunt voltage from the interpole field transformer 94 upon the interpole field winding.

Referring to Fig. 6, the circuit connections there shown are two sets of motors representing the commercial form of the invent-ion. The connections are provided to insure that the voltage-balancing relay 69 will not be made inoperative whenever any set of motors is cutout of circuit. In general, the system includes a combination of double-throw knife-blade switches for governing both the main and the auxiliary circuits in such manner that the actuating coil of the voltage-balancing relay 69 is transferred from connection across the terminals of one regenerative line switch if the corresponding set of motors is cut out of circuit to another regenerative line switch that is associated with an active set of motors.

The portion of the system illustrated comprises armatures A7 and A10 together with the corresponding inducing field windings C7 and C10, the regenerative line switches 33 311L134, the voltage-balancing relay 69, and a plurality of tl'ouble pole double-throw knife. switches 189r and 183.

Under normal conditions, that is, when all of the motors are to be connected in circuit, the switch 183 is thrown to its upper position, while the remaining knife-blade switch 182 occupies its lower position, as illustrated. Consequently, a circuit may be established from the conductor 301, which is connected to one terminal of the regenerative line switch 3 1, through interlocks 20- out and SO-out, actuating coil of the voltagebalancing relay 69, whence circuit is continud through switch jaws 202 and 205, which are bridged by the movable switch element or set of knife-blades 203, and conductor 172 to the opposite terminal of the regenerative line switch 3 1-.

The voltage-balancing relay 69 is thus adapted to perform its previously-described function, being connected across the stationary terminals of the switch 3%, as also illustrated in' 1. Thearmature A10 and the inducing field winding C10 are connected to switch jaw 206, whence circuit is cont-inucd through conductor 173, switch jaw 201, one part of the movable switch member 203 and the switch jaw 209 to the regenerative line switch 34, whereby the motor in question may be actively connected in circuit upon the closure of the switch 3%.

However, if it is found necessary to cut out of circuit the motor M10, then the voltage-balancing relay must be energized from another regenerative line switch in order to be enabled to perform its functions. Such transfer of connections is automatically *ffected by throwing the cutout switch 183 to its lower or cutout position. The circuit of the armature A10 is thus interrupted at switch jaw 201, but the circuit of the vol"- agc-balancing relay coil is continued from switch jaw 202 through movable switch member 203, switch jaw 20?, conductor 17 i, switch jaws 195 and 200, which are bridged by movable switch member 196, conductor 175 and switch jaw 199 to one terminal of. regenerative line switch 33. Consequently, the Voltagebalancing relay 69 is now connected across the terminals of the switch 33 and the normal functions of the relay will, therefore, be effected as previously described.

If an additional motor is connected in parallel to the motors M7 and M10, the previously unemployed jaw 198 is electrically connected to a central aw of a double throw two-blade switch that serves as a cutout switch of the additional motor.

In this way, the transfer of the voltagebalancin rela 69 to alwa s connect it with an active set of motors requires no extra thought or attention upon the 'part of the motorman when cutting out motors from circuit, since the usual actuation of the main motor-cutout switches automatically serves to reconnect the voltage-balancing relay to an active circuit.

I do not wish to be restricted to the specific circuit connections or arrangement of parts herein set forth, as various modifications thereof may be made without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicatedin the appended claims.

I claim as my invention:

1. In a system of control, the combination with an alternating-current commutator motor having an interpole field winding, of a i transformer for energizing the field winding, and means responsive to the load current adapted to automatically vary the ratio of the transformer primary and secondary voltages to vary the voltage applied to the interpole field winding.

9.. In a system of control, in combination, a source of power, an alternating-current commutator motor disposed to be connected across the power source, said motor being provided with an interpole field winding, a transformer for energizing said field winding, means manually operable to effect the application of a variable voltage to the transformer, and means responsive to the motor current to automatically vary the voltage applied to the interpole winding independently of the means provided for varying the volt- 'age applied to said transformer.

3. In a system of control, in combination, a source of power, an alternating-current motor disposed to be connected across the source of power, said motor being provided with an interpole field winding, a transformer for energizing said winding, means manually operable to effect the application of a variable voltage to the transformer, and means responsive to the motor current adapted to automatically vary the ratio of th primary and secondary voltages of said transformer to control independently the voltage applied to the interpole winding.

4. In a system of control, the combination with an alternating-current commutator motor having an interpole field winding, of a transformer for energizing said field winding, means for varying the available applied voltage to said transformer, a plurality of energy-supplying switches connected to different points in said transformer, and means responsive to the load current for selectively governing said switches.

5. In a system of control, the combination with an alternating-current commutator motor having an interpole field winding, ofa transformer for energizing said field winding, means for varying the available applied voltage to said transformer, a plurality of energy-supplying switches connected'to different points in said transformer, and a plurality of relay devices operating at different values of load current for selectively governing said switches.

6. In a system of control, the combination with an alternating-current commutator mo tor having an interpole field winding, of a transformer for energizing said field winding, means for varying the available applied voltage to said transformer, a plurality of electrically-controlled switches connected to different. points in said transformer, aplurality of relay means operating at difierent values of load current, and a plurality of transfer relay devices respectively de-energize-d when said relay means are actuated to selectively effect energization of said switches.

In testimony whereof, I have hereunto subscribed my name this 4th day of October 1923.

' LLOYD J. HIBBARD. 

